The Steel Guitar Forum

Ok......

Why do "most", even the solid state Combo Amps
have an open back but almost all extension Cabinets
have closed backs?

Someplace to stuff the power cord and footswitch, maybe? I always figured the tube amps were left open to keep them cool. Many early radio sets had open backs as well.

A number of Peavey's combo amps, particularly those marketed for keyboards, feature closed backs. They tune better than the open backed cabinets but as a result are harder to hear off axis, which is often the position of the player....

I did some research and here is what Fender says......

there are two kinds of speaker cabinet in this world—open back and closed back. Each design has a big effect on tone, so it’s an important consideration when formulating your own preferences and acquiring an amp. Here’s a primer on both types.

An open-back cabinet is one in which the speakers aren’t sealed inside the enclosure. That is, the back is open, or partially open. In this design, sound is less directional because it issues from the front and back of the enclosure, broadening its dispersion (coverage, basically) in the room. The sound seems to be “all around” the amp (your drummer, who is behind you onstage, will appreciate that).

Tonally, the open-back design contributes to less low-end punch and generally looser bass sound than a closed-back design. A great many guitar amps—combo amps in particular—use an open-back design.

Prime examples of current Fender open-back guitar amps range from the venerable ’65 Twin Reverb and ’59 Bassman LTD to modern amps such as the Mustang III and Frontman 212R.

In a closed-back cabinet, the speakers are sealed inside the enclosure. The back is closed, meaning that the sound is more directional because it issues only from the front of the enclosure. A closed-back cabinet lets you aim more of the power at the audience. It tightens sound dispersion in the room and imparts tighter and punchier bass to the overall sound.

In the early 1960s, Fender was one of the first amp makers to embrace closed-back design, as seen in pioneering piggyback guitar amps such as the Showman and Bandmaster. Further, because of the greater speaker articulation, the closed-back design dominates the bass amp world.

Prime examples of current Fender closed-back guitar amps include the Super-Sonic 60 Combo, Super-Sonic 100 412 enclosures, and extension cabinets for the (open-back!) Hot Rod Deluxe and Vibro-King Custom.

With an open back cabinet, you can enhance the sound by placing it up against a wall.

Now, I find if I place my amp up against the wall, my tone goes to hell. I end up chasing the sound all night. In places where I can be 3 or more feet from the back wall, my amp sings. In those situations, I rarely, if ever, have to touch any of the tone controls to change from my "normal" sound. I have a base setup for all my controls, including pre and master gains. Most places I play are the same size and we play about the same volume. I only touch my pre-gain control if the venue requires a really low volume. The rest of the time, my volume is controlled with my volume pedal and right hand. Amp against the wall, and I would rather stay home and watch TV.

I'm with Richard. I can't stand having my amp against a wall. Even worse, curtains hanging behind a stage can kill the sound of an amp, if it's placed too near the curtains.

The ultimate crap situation is a club I play at about once a month. First off, I have to sit on the floor and deal with people tripping over my guitar on the way to the dance floor (I am thinking of re-arranging the tables to block them), My amp is right against the wall and the front of the amp is about 4 inches from my back, but a little to the side. There is no way to sound good with that setup. To top it off, I have a monitor (the guitar player's) aimed right at me and the PA main speaker just off to my left aimed straight out. Both are too loud and it's like I have earphones full of vocals on my head.

Maybe you should just stay home and watch TV.

Don't have TV access here or I probably would.

Fortunately, this place has a TV directly across from the stage and dance floor, so I can watch for the first hour or so before they get smart enough to realize it is on and turn it off.

Virtually every 1x12 and 2x12 extension cab that I own is open-backed because I generally play single coils (Strat/Tele), and I prefer an open, airy (black-faced) sound, but if I'm after something that's a bit more 'in your face' (like an R9 with humbuckers through a Marshall Plexi or SLO), then I want the focused edginess provided by closed-back cabs.

Combo amps require cooling, and a place to store cords and pedals, whereas speaker-only cabinets do not. Normally, closed cabinets are far more efficient, and give far better bass response.